Firstly, I bought two of these JVS I/O from here Aliexpress I/O as it is a copy of the famous CAPCOM I/O people rave about. The reason why I chose this over a used SEGA or CAPCOM one is because it is brand new and the price is reasonable. The I/O draws current from the JAMMA harness so it will be used as often as the cabinet is powered on, the mileage of a second hand one can vary and could die at anytime.The package came with the wrong RCA cables (RCA to 3.5mm headphone jacks were dispatched instead...which is awesome because I needed a couple of those, score~) and a set of JVS power plugs which will make sense if there is a header next to the DSUB plug, which is not the case here. Any how, it is best practice to power the Naomi 2 motherboards with another power supply instead of relying on the I/O. The other function of the I/O include amplifying the sound from the motherboard to JAMMA level, JVS controls to digital JAMMA standards (a bit on this later), passing through video signal (RGBHV/RGBS) to the JAMMA edge and allowance for a CPS2/3 Kick Harness to accomodate the extra inputs on certain games (again, a bit on this later). What is unique about this I/O versus the SEGA one is that it can allow up to 4 Players on certain games like PowerStone, but the trade off is you can not use any analog controls on the board. The build quality is pretty good, no hot glue for jumps or bad soldering jobs. The only gripe I have with it is the misdirection on production and the lack of an information leaflet.
This is how it looks like once interfaced with the Naomi 2 (or 1) with a Naomi 1 cartridge inserted. The JVS powerline is present on the Blast City's -001 loom so the two connectors plug directly into the motherboard. Then its a matter of plugging the serial USB plug, RCA audio and DSUB into the I/O. At this point you might want to toggle the jumper on the filter board to output 15KHz as that will be what the cabinet is expecting at the JAMMA edge. As the I/O is more or less a passive adapter, it will not matter whether you power on the Naomi 2 or the I/O first. In this case, both are on at the same time as power is coming from the same power supply. The Naomi 2 fan is comparable to the CPS2 one so its rather loud, but unlike the CPS2 one, you really need them running with the fan on as the chips get very hot over time.
With luck, you should see this going on the screen. I do not think the 15KHz image directly from the Naomi 2 is ideal for me as the image is interlaced, so outlines are blurred and the image is not 100% stable. The better way to display this is setting the Naomi 2 to 31KHz on the jumper and plugging the DSUB directly to the monitors DSUB input. That way the image is in progressive mode, plus you can reintroduce scanlines if you wish with any SLG (ScanLineGenerator) on the market or build one yourself.
And the same here for the second setup:
I was very comfortable with the setup, until this happened:
As you can see, both player 1 and player 2 has Shot 6 activated eventhough I had nothing plugged into the Kick harness port. How odd and frustrating. I cross checked my setup on a second cabinet as well to make sure the problem is not an isolated case and it was happening on whatever setup I had. So my next step is to obtain some help from the sellers of the various components.
The best hint I got was from Chloe from Highway Entertainment where I got the Naomi 2 motherboards from. Her advice was that all was not what it seem on the JAMMA pinout of the I/O, which made sense as I know of the infamous Blue Elf reincarnations which capitalised on the unused JAMMA pinouts for the extra Shot buttons.
So compare this:
The last 2 pairs of pins on a JAMMA standard are both grounded together and that corresponds to Button 6 for both players. So logic has determined that the Chinese manufacturers of the I/O will follow the Chinese made Blue Elf boards. So its time to test the theory.Que Macgyvers theme...
And what do you get?
Have not diffused a bomb but equally satisfying.
I tested the Kick harness with a makeshift wire and paper clip combo as I was in the Macgyver mood and all the Kick buttons are working as they should. Could this be a redundancy precaution taken by the manufacturers of the I/O should the kick harness kick the bucket? Nobody will ever know.
And finally, the Kick harness and header issue. Honestly, I do not care what was the designers motivation here? Does he/she dislike propriety plugs? Dislike standard JAMMA conventions? Though people will not use the connector because the ChAMMA convention was the standard?? There is no way to get this plug to work unless I void the I/O's warranty or is there?